/*
 * v4l2_capture_example.c
 * V4L2 video capture example
 * AUTHOT : WANGTISHENG
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <getopt.h> /* getopt_long() */
#include <fcntl.h> /* low-level i/o */
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#include <linux/videodev2.h>

#define CLEAR(x) memset(&(x), 0, sizeof(x))

struct buffer {
    void *start;
    size_t length;
};

static int fd = -1;        //DEVICE NUMBER
struct buffer *buffers;
static unsigned int n_buffers ;
static char dev_name[64] = {};
static int frame_count = 1;
static int expo_time = 4;

static void errno_exit(const char *s)
{
    fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
    exit(EXIT_FAILURE);
}

static int xioctl(int fh, int request, void *arg)
{
    int r;
    do {
        r = ioctl(fh, request, arg);
    } while (-1 == r && EINTR == errno);
    return r;
}
//处理函数
static void process_image(const void *p, int size)
{
}

static int read_frame(FILE *fp)
{
    struct v4l2_buffer buf;
    CLEAR(buf);

    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    buf.memory = V4L2_MEMORY_MMAP;

    if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) 
        errno_exit("VIDIOC_DQBUF");

    fwrite(buffers[buf.index].start, buf.bytesused, 1, fp); 
    //process_image(buffers[buf.index].start, buf.bytesused);

    if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
        errno_exit("VIDIOC_QBUF"); 

    return 1;
}

static void mainloop(void)
{
    unsigned int count = 0;
    char img[16] = {"img_00.jpg"};
    while (count++ < frame_count) {
        FILE *fp;
        *(short *)(&img[4]) = 0x3030 | (count%10 << 8) | (count/10);
        printf("No.%02d, %s\n", count, img);
        if ((fp = fopen(img, "w")) != NULL) { 
            read_frame(fp);
        }
    }
    printf("\nREAD AND SAVE DONE!\n");
}

static void stop_capturing(void)
{
    enum v4l2_buf_type type;

    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))
        errno_exit("VIDIOC_STREAMOFF");
}

static void start_capturing(void)
{
    unsigned int i;
    enum v4l2_buf_type type;

    for (i = 0; i < n_buffers; ++i) {
        struct v4l2_buffer buf;

        CLEAR(buf);
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = i;

        if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
            errno_exit("VIDIOC_QBUF");
    }
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
        errno_exit("VIDIOC_STREAMON");
}

static void uninit_device(void)
{
    unsigned int i;

    for (i = 0; i < n_buffers; ++i)
        if (-1 == munmap(buffers[i].start, buffers[i].length))
            errno_exit("munmap");

    free(buffers);
}

static void init_mmap(void)
{
    struct v4l2_requestbuffers req;
    CLEAR(req);

    req.count = 4;
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory = V4L2_MEMORY_MMAP;

    if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
        if (EINVAL == errno) {
            fprintf(stderr, "%s does not support memory mapping\n", 
                    dev_name);
            exit(EXIT_FAILURE);
        } else {
            errno_exit("VIDIOC_REQBUFS");
        }
    }

    if (req.count < 2) {
        fprintf(stderr, "Insufficient buffer memory on %s\n",
                dev_name);
        exit(EXIT_FAILURE);
    }

    buffers = (buffer *)calloc(req.count, sizeof(*buffers));

    if (!buffers) {
        fprintf(stderr, "Out of memory\n");
        exit(EXIT_FAILURE);
    }

    for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
        struct v4l2_buffer buf;
        CLEAR(buf);

        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;
        buf.index = n_buffers;

        if (-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf))
            errno_exit("VIDIOC_QUERYBUF");

        buffers[n_buffers].length = buf.length;
        buffers[n_buffers].start =
            mmap(NULL /* start anywhere */,
                    buf.length,
                    PROT_READ | PROT_WRITE /* required */,
                    MAP_SHARED /* recommended */,
                    fd, buf.m.offset);

        if (MAP_FAILED == buffers[n_buffers].start)
            errno_exit("mmap");
    }
}

static void init_device(void)
{
    struct v4l2_capability cap; //查询设备功能

    if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap)) {//测试参数
        if (EINVAL == errno) {
            fprintf(stderr, "%s is no V4L2 device\n",
                    dev_name);
            exit(EXIT_FAILURE);
        } else {
            errno_exit("VIDIOC_QUERYCAP");
        }
    }

    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
        fprintf(stderr, "%s is no video capture device\n",
                dev_name);
        exit(EXIT_FAILURE);
    }

    if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
        fprintf(stderr, "%s does not support streaming i/o\n",
                dev_name);
        exit(EXIT_FAILURE);
    }

    //struct v4l2_control ctrl;
    //CLEAR(ctrl);

    //ctrl.id = V4L2_CID_FOCUS_AUTO;
    //ctrl.value = false;
    //printf("focus: %d\n", ctrl.value);
    //if (-1 == xioctl(fd, VIDIOC_G_CTRL, &ctrl))
    //    errno_exit("VIDIOC_G_CTRL");
    //printf("focus: %d\n", ctrl.value);

    //ctrl.id = V4L2_CID_FOCUS_ABSOLUTE;
    //ctrl.value = -1;
    //printf("focus: %d\n", ctrl.value);
    //if (-1 == xioctl(fd, VIDIOC_G_CTRL, &ctrl))
    //    errno_exit("VIDIOC_G_CTRL");
    //printf("focus: %d\n", ctrl.value);

    //struct v4l2_queryctrl query;
    //CLEAR(ctrl);
    //for(int i = 0; i < 10; i++){
    //    ctrl.id = V4L2_CID_FLASH_CLASS;
    //    ctrl.value = 1;
    //    if (-1 == xioctl(fd, VIDIOC_G_CTRL, &ctrl)){
    //        errno_exit("VIDIOC_G_CTRL");
    //    }
    //    printf("ctrl: %d\n", ctrl.value);
    //}
    
    struct v4l2_control ctrl;
    // 查询曝光模式
    ctrl.id = V4L2_CID_EXPOSURE_AUTO;
    if (-1 == xioctl(fd, VIDIOC_G_CTRL, &ctrl)) {
        printf("Get exposure auto Type failed\n");
        errno_exit("VIDIOC_G_CTRL");
    }
    printf("Get Exposure Auto Type:[%d]\n", ctrl.value);

    // 设置曝光模式为手动模式
    ctrl.id = V4L2_CID_EXPOSURE_AUTO;
    ctrl.value = V4L2_EXPOSURE_MANUAL;   //手动曝光模式
    if (-1 == xioctl(fd, VIDIOC_S_CTRL, &ctrl)) { 
        printf("Get exposure auto Type failed\n");
        errno_exit("VIDIOC_S_CTRL");
    }

    // 查询曝光值
    ctrl.id = V4L2_CID_EXPOSURE_ABSOLUTE;
    if (-1 == xioctl(fd, VIDIOC_G_CTRL, &ctrl)) {
        printf("Set exposure failed\n");
        errno_exit("VIDIOC_G_CTRL");
    }
    printf("Get ABS EXP Success: [%d]\n", ctrl.value);

    sleep(1);

    //设置曝光绝对值
    ctrl.id = V4L2_CID_EXPOSURE_ABSOLUTE;
    ctrl.value = expo_time;
    if (-1 == xioctl(fd, VIDIOC_S_CTRL, &ctrl)) {
        printf("Set exposure failed\n");
        errno_exit("VIDIOC_S_CTRL");
    }

    struct v4l2_format fmt;//帧格式
    CLEAR(fmt); 

    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width = 3264;
    fmt.fmt.pix.height = 2448;
    //fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_JPEG;
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;

    if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))        //设置格式
        errno_exit("VIDIOC_S_FMT");        
    printf("pixelformat: %08x\n", fmt.fmt.pix.pixelformat);
    init_mmap();
}

static void close_device(void)
{
    if (-1 == close(fd))
        errno_exit("close");

    fd = -1;
}

static void open_device(void)
{
    //加上O_NONBLOCK会出现如下错误
    //VIDIOC_DQBUF error 11, Resource temporarily unavailable
    fd = open(dev_name, O_RDWR /* required */ /*| O_NONBLOCK*/, 0);

    if (-1 == fd) {
        fprintf(stderr, "Cannot open '%s': %d, %s\n",
                dev_name, errno, strerror(errno));
        exit(1);
    }
}

int main(int argc, char **argv)
{
    strcpy(&dev_name[0], "/dev/video0");
    expo_time = 4;
    frame_count = 1;

    int opt=0;
    while((opt = getopt(argc, argv, "d:c:t:")) != -1) {
        //optarg is global
        switch(opt) {
            case 'd':
                memset(&dev_name[0], 0, 64);
                strcpy(&dev_name[0], optarg);
                printf("DevName: %s\n", dev_name);
                break;
            case 'c':
                frame_count = atoi(optarg);
                printf("Count: %d\n", frame_count);
                break;
            case 't':
                expo_time = atoi(optarg);
                printf("ExpoTime: %d\n", expo_time);
                break;
            default:
                //非法参数处理，也可以使用case来处理，？表示无效的选项，：表示选项缺少参数
                exit(1);
                break;
        }
    }

    open_device();//打开设备
    init_device();//查询，设置视频格式
    start_capturing();//请求分配缓冲，获取内核空间，
    mainloop();//主要处理均在该函数中实现

    stop_capturing();
    uninit_device();
    close_device();
    //fprintf(stderr, "\n");
    return 0;
}
